<table class="library">
<tr>
    <th>Prefix</th>
    <th>Field Description</th>
</tr>
<tr>
  <td>Ball</td><td>BGA Ball diameter</td>
</tr>
<tr>
    <td>Clearance</td><td>Clearance between pin rows</td>
</tr>
<tr>
    <td>Drill</td><td>Drill diameter</td>
</tr>
<tr>
    <td>Layout</td><td>Specific footprint layout<br>e.g. <code>Layout3x7</code> for a BGA with 21 balls arranged in 3 columns and 7 rows</td>
</tr>
<tr>
    <td>Lead</td><td>Lead dimensions</td>
</tr>
<tr>
    <td>Mask</td><td>Custom soldermask dimensions</td>
</tr>
<tr>
    <td>Pad</td><td>Custom pad dimensions</td>
</tr>
<tr>
    <td>Tab</td><td>Tab dimensions</td>
</td>
</table>